Improvement in pistons for, steam-cylinders



UNITED STATES PATENT QEEICE.

MATTHEW B. MASON, OF AURORA, INDIANA,'ASSIGNOR TO HIMSELF AND GEORGE W.HARRIS.

IMPROVEMENT IN PISTONS FOR.STEAMCYL|NDERS.

Specification forming part of Letters Patent No. 57,823, dated September4, 1866.

lfor the introduction of steam to the interior of the piston head, inorder to expand the packin g-rin gs bystearn-pressure; and'itfurtherconsists in a novel construction ot' the packing-rings, whereby they areso held together as to prevent twisting on the head, and are adapted toexpand equally the entire width of the piston-face.

Figure l represents in detail perspective views ot a piston-headembodying my invention. Fig. 2 is an axial section ofthe same head. Fig.3 is an axial section showing a modification of my improvement.

A is the follower B, the piston-head proper; C, the spider, boredforconnecting-screws, E, the rod, and F the tightening-key.

G is a solid ring, made to tightly embrace the spider C. It is groovedon its periphery g g', the grooves having communication with theinterior of the head throughl any number of 1,)erforations a.

rlhe piston-head proper, B, and follower A are suitably pierced andchamfered inside to form seats for the double-headed valves H. The twobearing-faces of each double-headed valve are slightly nearer togetherthan the distance between the seats, to enable the valves to have aslight longitudinal motion, changing automatically to admit steam on thepressure side of the piston, and by the same motion closing on theexhaust.

The valve-stems are grooved at the ends to form steam-passages. Therequired pressure is thus retained within the piston-head at all timesto serve the purpose ot' packing' the piston-rings, and at the same timeto prevent all escape by the exhaust.

I I J are the packing-rings, cut as shown at t", and kept in place onthe piston-head Aby means of projecting pin K. The rings I I have therepresented L shape in transverse section to extend in the interiortogether the entire width of the ring` G, and channeled from theexterior to contain the middle ring, J.

It will thus be seen that the steam admitted at perforations a. c actsto force the rings I I J out together the entire width of packingface atalltimes, and that the rings are so connected togetherthat, it' thepiston were allowed to extend nearly two-thirds the width ot'packing-face past the ports of the cylinder, none vof the rings couldescape.

In Fig. my improvements are modified by casting the ring G in one piecewith the piston-head and .dispensing with the spider C. This is thepreferred t'orm for `new pistons.

The number of valves and size ot" grooves should be so arranged as tosecure the requisite steam-pressure within the head.

I claim herein as new and ot' my invention- 1. The arrangement of theL-shaped packin g-rings I I and middle rin g, J, as described, and forthe purpose specilied.

2. The grooved and perforated ring Gr, con-

